Update docs

CHANGELOG.asciidoc

@@ -33,6 +33,9 @@ Added
 - New `{clipboard}` and `{primary}` replacements for the commandline which
   replace the `:paste` command.
 - New `:window-only` command to close all other windows.
+- New `prev-category` and `next-category` arguments to `:completion-item-focus`
+  to focus the previous/next category in the completion (bound to `<Ctrl-Tab>`
+  and `<Ctrl-Shift-Tab>` by default).
 
 Changed
 ~~~~~~~

doc/help/commands.asciidoc

@@ -1006,7 +1006,7 @@ Syntax: +:completion-item-focus 'which'+
 Shift the focus of the completion menu to another item.
 
 ==== positional arguments
-* +'which'+: 'next' or 'prev'
+* +'which'+: 'next', 'prev', 'next-category', or 'prev-category'.
 
 [[drop-selection]]
 === drop-selection